NJM2537
FM IF IC FOR PAGERS
■
GENERAL DESCRIPTION
The
NJM2537
is a low power FM IF IC for pagers.
It is capable of designing dual conversion pager system because
of including a mixer circuit. Also it includes RSSI function, so that it is
easy to design automatic gain control (AGC) which improves
interberence when strong signal is received.
■PACKAGE
OUTLINE
NJM2537V
■
FEATURES
●
Low Operating Voltage
●
Low Operating Current
●
RF Input Frequency
●
2nd Mixer
●
Package Outline
1.1 to 4.0V
1.2mA typ.at V
+
=1.4V
10 to 50MHz
SSOP20
■
PIN FUNCTION AND BLOCK DIAGRAM
1.
2.
3.
4.
5.
6.
7.
8.
9
10.
OSC IN
OSC OUT
MIXER OUT
V
+
IF IN
DECOUPLING
FSK REF
QUAD IN
AF OUT
RSSI
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
LPF IN
LPF OUT
BS
CHARGE
FSK OUT
VALM
REG CONT
REG OUT
GND
MIXER IN
Ver.2003-12-09
-1-
NJM2537
■
ABSOLUTE MAXIMUM RATINGS
PARAMETER
Supply voltage
Power Dissipation
Operating Temperature Range
Storange Temperature Range
SYMBOL
V
CC
P
D
T
opr
T
stg
RATINGS
4.0
300
-30 to +85
-40 to +125
(T
a
=25°C)
UNIT
V
mW
°C
°C
■
ELECTRICAL CHARACTERISTICS
PARAMETER
No Signal Operating Current
Battery Saving
Operating Current Mixer Gain
Mixer Intercept Point
Mixer Input Resistance
Mixer Output Resistance
IF Amplifier Input Resistance
S/N1
S/N2
S/N3
-3dB Limiting Sensitivity 1
-3dB Limiting Sensitivity 2
Demodulated Output Level
AM Rejection Ratio
Duty Ratio at Wave Shaped Output
RSSI Output Voltage
RSSI Output Resistance
Quick Charge / Discharge Current
Alarm Detection Voltage
Regulator Output Voltage
Low level Output Voltage
of VALM Terminal
High Level Leak Current
of VALM Terminal
Low Level Output Voltage
of FSK-OUT Terminal
High Level Leak Current
of FSK-OUT Terminal
Low Level Output Voltage
of REG-OUT Terminal
SYMBOL
I
CCq
I
CCS
GMIX
IP
R
in
MIX
R
O
MIX
R
in
IF
S/N1
S/N2
S/N3
LIM1
LIM2
Vod
AMR
DR
V
rssi
R
rssi
I
ch
Valm
Vreg
ValmL
IalmH
VfskL
IfskH
VregL
(V
+
=1.4V, f
C
=21.7MHz, fIF=455kHz, fmod=600Hz, fdev=±4kHz, T
a
=25°C)
TEST CONDITION
MIN.
-
-
After Ceramic Filter
11
-
-
-
-
MIXER Input, V
I
=60dBµVEMF
IF Input, V
I
=60dBµVEMF
IF Input, V
I
=22dBµVEMF
MIXER Input
IF Input
IF Input, V
I
=60dBµVEMF
IF Input, V
I
=60dBµVEMF, AM=30%
IF Input, V
I
=60dBµVEMF
IF Input, V
I
=65dBµVEMF
GND, 0.18V
RL=430Ω
IL=100µA
-
-
-
-
-
30
-
40
0.48
-
40
1.05
0.95
-
-
IL=100µA
-
-
IL=100µA
-
TYP.
1.2
0
14.5
103
5
2
2
63
63
25
12
22
46
50
50
0.62
62
70
1.10
1.00
0.1
0
0.1
0
-
MAX.
1.5
5
18
-
-
-
-
-
-
-
17
27
65
-
60
0.76
-
115
1.15
1.05
0.4
2
0.4
2
0.6
UNIT
mA
µA
dB
dBµVEMF
kΩ
kΩ
kΩ
dB
dB
dB
dBµVEMF
dBµVEMF
mVrms
dB
%
V
kΩ
µA
V
V
V
µA
V
µA
V
-2-
Ver.2003-12-09
NJM2537
■
APPLICATION CIRCUIT
Ver.2003-12-09
-3-
NJM2537
■
TERMINAL FUNCTION
PIN NO.
SYMBOL
PIN VOLTAGE (V)
FUNCTION
Local Oscillator Input.
In case of using a crystal
oscillator, it is connected.
EQUIVALENT CIRCUIT
1
OSC IN
1.38
2
OSC OUT
0,68
Local Oscillator Output.
In case of using an external
oscillator, the external clock is
input.
Mixer input.
Input resistance is 5kΩ typical.
20
MIX IN
0.8
Mixer output.
Output resistance is 2kΩ
typical.
3
MIX OUT
0.7
5
IF IN
1.38
Limiter amplifier input.
Input resistance is 2kΩ typical.
Decoupling for bias.
6
DEC
1.38
8
QUAD IN
1.4
Input of quadrature detection
circuit.
A ceramic discriminator is
connected.
Demodulated signal Output.
9
AF OUT
0.16
-4-
Ver.2003-12-09
NJM2537
■
TERMINAL FUNCTION
PIN NO.
SYMBOL
PIN VOLTAGE (V)
FUNCTION
RSSI output
EQUIVALENT CIRCUIT
10
RSSI
0
Input of a low pass filter. It is
biased from AF-OUT (9pin)
through an external RC filter.
11
LPF IN
0.18
Output of a low pass filrter.
12
LPF OUT
0.18
7
FSK REF
0.18
Reference input of a wave
shaping comparator.
An external capacitor is
connected.
13
BS
-
Control of a battery saving
circuit.
Hi : active
Lo : suspended
14
CHARGE
-
Control of a quick charge /
discharge circuit.
Hi : Its circuit turns ON
Lo : Its circuit turns OFF
15
FSK OUT
-
Output of a wave shaping
circuit. The output signal is
inverted against LPF output
signal.
Ver.2003-12-09
-5-
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